Eighty percent of the world's arable land is currently being used to provide food for the Earth's estimated 6.8 billion people. If trends continue, the United Nations predicts that the population will exceed 9 billion by 2050. Using existing agricultural practices, we would need an additional one billion acres of land to feed everyone.

That's land we simply don't have. Add to this the rising price of oil, which dramatically affects both the cost of shipping food and many of the fertilizers used to produce it, as well as the growing demand for feed stocks such as corn to produce ethanol and the impact of climate change on agricultural production, and it would appear that we are only a few bushels away from a global famine.

That is unless you talk to Gordon Graff, a graduate student at the University of Waterloo. Using his passion for sustainability and his knowledge of architecture, Graff has created a number of vertical farming concepts that shatter the urban design paradigm and redefine the idea of local agriculture.

The first is a visionary 59-storey building that Graff calls a Sky Farm. Utilizing the principles of hydroponic gardening to maximize food production, his design translates 3.8 million square feet of floor space into 11 million square feet of growing area all on a mere 1.32 hectares. By his own estimate, the Sky Farm could produce 54 million pounds of fruits and vegetables, nearly a million pounds of animal meat and nearly a half a million pounds of eggs - enough food to feed 40,000 people year round. A ground level grocery store could sell the produce, making the entire food cycle carbon neutral.

The building's heating and lighting are provided by a wall of photovoltaic cells and a Living Machine - an anaerobic digester that uses organic wastes from the gardens and an exterior grow wall (depending on the climate) to produce power and filter waste water. By also capturing waste methane from the city's sewer system, Gordon estimates his Sky Farm could even produce electricity that could be fed back to the grid.

Graff's second design, Grow Housing, incorporates a smaller version of the Sky Farm into a low-rise city block development that includes condominium and town house units, a grocery market, and street level retail and commercial space. The complex is topped off with a green rooftop that is designed to function as a community garden for low-income earners.

Graff, who will complete his graduate degree this fall, has already accepted a position with Cohos Evamy, an innovative architectural and design firm. He's optimistic that through necessity, his visionary designs will soon become a reality.

"Vertical farming is inevitable," said Graff. "There is no alternative to this form of agriculture. There are other strategies that make sense for energy and carbon footprint, but not necessarily in terms of food supply."